Bank doesn't want to release the funds

Hi my name is AGRINATH MAZIBUKO my mother Mazibuko CHITHEKILE BEAUTY had a account with ABSA she passed away it's been 2 years the is a remaining balance in her account they said I must come back after the funeral for the balance I went back I filled the form and have them a letter of authority so that they can release the funds till today I have not received anything I went back last week they made fill the form again it the branch in JABULANI mall.